Two-stroke cycle internal-combustion engine



Sept. 22, 1953 F. J. NEUGE QBAUER TWO-STROKE CYCLE INTERNAL-COMBUSTION ENGINE Filed May 20, 1952 Patented Sept. 22, 1953 UNITED STATES PATENT OFFICE TWO-STROKE CYCLE INTERNAL- COMBUSTION ENGINE Franz J. Neugebauer, Schenectady, N. Y.

Application May 20, 1952, Serial No. 288,993

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

Thi invention relates to internal combustion engines and in particular to scavenging in a two cycle diesel or gasoline engine.

In designing internal combustion engines of the two stroke cycle type for efiicient scavenging it is desirable to have a row of large exhaust ports arranged about the circumference of the cylinder wall to permit substantially unrestricted air flow from the cylinder. This is particularly true with rising R. P. M. of the engines made today, wherein a shorter time is now available for exhaust gas to escape. It is also desirable to have a row of inlet openings in the cylinder wall for scavenger air arranged immediately below and in close proximity to the exhaust ports. The reason for positioning the air inlet openings immediately below the exhaust ports is to maintain the height of the openings and ports at a minimum and maintain as large and effective working stroke as possible. However, when the exhaust ports and inlet openings are in this close proximity relationship, the walls of the cylinder become greatly weakened, and the explosive forces exerted in the cylinder will tend to blow the top portion of the cylinder off. In order to overcome this objection, it is an object of this invention to provide a strengthening means for carrying the explosive forces and stresses created in the cylinder away from the cylinder wall and still maintain the close proximity of the exhaust ports and air inlet openings.

It is a further Object of this invention to provide a sleeve attached to a cylinder wall above the exhaust ports therein, the said sleeve being connected to a crankcase whereby the forces exerted on the cylinder Wall can be carried through the sleeve to the crankcase.

It is a further object of this invention to maintain the rows of exhaust ports and inlet openings in as close proximity as possible in order to maintain the lost portion of the stroke at a minimum. These and other objects of this invention will become more apparent when read in the light of the specification and drawings wherein similar parts have the same numbers and wherein;

Figure 1 shows a cross sectional view of the inlet ports in the cylinder wall of a two cycle engine.

Figure 2 is a cross sectional view of a two cycle diesel engine provided with the strengthening means of this invention.

Referring to Figures 1 and 2, 2D refers to a two cycle engine having a cylinder 22 provided with a piston 24. The cylinder wall 26 is provided with a threaded annulus 28 and exhaust ports 30 which extend in a downward direction (Figure 2) which direction is in the path of the exhaust gas. The cylinder wall is also provided with a group of inlet openings 32 immediately-below the exhaust ports 30 for scavenging air.

The said exhaust ports 30 and scavenging air inlet openings 32 are arranged about the circumference of the cylinder in as close proximity as is structurally feasible with the inlet openings 32 also extending in a downward direction (Figure 2) which direction is in the path of the scavenging air. The said scavenging air inlet openings 32 may be directed radially or tangentially to a circle located within the cylinder concentrically about the axis of the cylinder (Figure l) A sleeve or collar 34 is provided with a counterbore 35 with threads therein and is threadably mounted'upon the annulus 28. The sleeve 34 is provided with ports 40 which are in alignment with exhaust ports 30 in the cylinder Wall. An exhaust manifold i2 is connected to the sleeve 34. The sleeve 34 is spaced from the cylinder wall 26 to provide passageways 44 for the passage of scavenging air to the inlet ports 32 and to the cylinder 22. Sleeve 34 is connected at its other end to the crankcase 52 by bolts 5.8. The crankcase 52 is provided with ducts 50 which ducts are in alignment with the passageways 34 for the passage of scavenging air. The crankcase 52 is also provided with integral crankshaft webs having bearings 54 therein.

In operation, when the piston uncovers the exhaust ports and inlet openings on its downward stroke the combustion gases are scavenged from the cylinder by air being injected under pressure by a blower 56 or the like, into the cylinder through the air inlet openings located immediately below the exhaust ports. Since the exhaust ports are relatively larger than the inlet openings, the combustion gases have a better opportunity of being scavenged from the cylinder. However, since the cylinder Wall is provided with large exhaust ports for greater scavenging efiiciency, and the exhaust ports and air inlet openings are in close proximity to maintain the lost portion of the stroke at a minimum, the cylinder wall has become weakened. The explosive forces in the cylinder tend to normally create large stress concentrations around this portion of the cylinder wall. These forces are carried from the cylinder wall through the annulus 28, to the sleeve 34, down to the crankcase 52, through the webs, and to the bearings 54. I

A swirl of air movement in the cylinder is created if the air scavenging inlet ports are directed tangentially to the desired swirl. The swirl of the scavenging air will continue until the air leaves the cylinder through the exhaust ports. The fact that the exhaust ports are large to permit substantial unrestricted air flow and that the scavenging air inlet openings are inclined downwardly to direct the scavenging air away from the cylinder head will create a situation in the cylinder whereby the inlet air under .pressure from the blower will occupy the center of the cylinder and the exhaust air will occupy the space near the cylinder wall so as to create a movement of air upward from the inlet ports to the top of the cylinder and then downward toward the exhaust ports. For this reason the said inlet openings and exhaust ports are inclined downwardly in the direction of the air flow. In this manner high scavenging efiiciency and intimate fuel-air mixture is obtained, whereby the efficiency of the engine is increased.

It is apparent that the specific embodiments shown above have been given by way of illustration and not by way of limitation and that the structures above described are subject to wide variation and modification without departing from the scope or intent of the invention, all of which variations and modifications are to be considered as equivalents and be included within the scope of the present invention.

Whereby I claim:

1. In a two cycle engineprovided with a cylinder, piston and crankcase, means for maintaining the lost portion of the piston stroke as small as possible,- said means comprising a series of exhaust ports spaced about the circumference of the center portion of said cylinder in juxtaposition above a series of groups of scavenging air inlet openings, each group being symmetrically spaced about the circumference of said cylinder, said exhaust ports and said inlet openings inclined downward in the direction of the air flow therethrough, means for transmitting the explosive forces away from the weakened portion of the cylinder wall caused by the close proximity of the exhaust ports and inlet openings, said means comprising a collar threadably mounted on the cylinder at one end, and connected to the crankcase at the other end,

whereby the forces due to the pressure exerted on the cylinder wall is carried by the collar to the crankcase, said collar is provided with ports which are in alignment with the exhaust ports in said cylinder wall and which enter into an exhaust manifold connected to said collar, the said collar being spaced from said cylinder to form a passageway, a duct in the crankcase for the entrance of scavenging air into said passageway in the collar, the said passageway connected with the inlet opening for the passage of scav enging air into the cylinder.

2. In an internal combustion engine of the two cycle type provided with a piston cylinder and crankcase, exhaust ports in the cylinder wall suificiently large in area to permit substantially unrestricted air flow therethrough, and groups of air inlet ports in close proximity with said exhaust ports so as to keep the lost portion of the piston stroke at aminimum, said crankcase being provided with crankshaft supporting webs, bearings mounted in said webs for carrying a .crankshaft, a sleeve mounted on said crankcase and threadedly connected to said cylinder,

wall, said sleeve being spaced-from said cylinder wall to vform a passageway for air flow therethrough to said air inlet openings, said sleeve being counterbored and threaded so as to receive I a threaded annulus on said cylinder wall, said annulus being positioned immediately above the exhaust ports and air inlet openings so as to carry the forces from said cylinder wall, which has been weakened by the close proximity of the said exhaust ports and air inlet openings, through the sleeve and crankcase webs, then to the bearings and crankshaft, said sleeve having ports in alignment with the exhaust ports in said cylinder wall, and an exhaust manifold connected to said sleeve, a partition between said ports and openings in said sleeve for separating the exhaust gas from the inlet scavenging air.

FRANZ J. NEUGEBAUER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,664,782 Magdeburger Apr. 3, 1928 1,703,718 Brown Feb. 26, 1929 1,862,640 Trechsel June 14, 1932 2.209.996 Neuland Aug. 6, 1940 

